Vulcanization of rubber and products obtained thereby



Patented Dec. 17, 1935.

i UNITED STATES VULCAN I ZATION OF RUBBER PROD UCTS 'oBTAlNEfl' THEREB-Y 'Win'fild 'scott, Nitro, W. Va... assignor to The Rubber Service Laboratories Ohio, a corporation of Ohio k r I :Application T September 29, I932,

. Serial No. 635,403

:No Drawing.

Company, Akron,

The present invention relates 'to the manufacture :of a vulcanized rubber product by'an improved process wherein there is employed, .in addition to the ordinary compounding ingredients, a new type of reaction product capable-of imparting age resisting or anti-oxidant characteristics to the rubber product.

It is well known to rubber chemists that the use of certain vulcanization accelerators in the curing of rubber isriobjectionable since the presence of such compounds or of their heat of decomposition or sulfur or other reaction products produced in the rubber curing process apparently cause or aid in causing a relatively rapid deterioration of the vulcanized products. Such rubber products are said to age badly, that is, the rubber becomes hard and loses a large part of its resiliency, while other characteristics such as tensile strength and the like are very detrimentally affected.

The age resisting characteristics of a vulcanized rubber product can be readily ascertained by subjecting samples of the vulcanized product in a bomb to the action of oxygen under pressure.

and maintained for several hours at an elevated temperature. The treated samples are then examined and tested and the results compared with similar results obtained by vulcanized stock. The deterioration in properties, suffered as a result of the oxidation treatment is indicative of the result that normally would be expected from that particular stock during service. Such a test is known as the Bierer- Davis aging test and pro'duces an elfect on a vulcanized rubber stock comparable with that resulting from several years of natural aging of the rubber.

According to the present invention, a new class of anti-oxidants has been found which, upon incorporation in a rubber sto'ck, imparts the de sired age resisting qualities to the vulcanized stock. The compounds imparting such antioxidant characteristics to vulcanized rubber as disclosed in the present specification comprise the sulfur reaction products of diarylamine compounds. The present invention will be fully understood from the following descriptionrand examples.

testing the unaged a-mthod illustrative of'the preparation of the preferred class of compounds, substantially one-molar portion of di beta-naphthy'lamine and approximately two atomic weight portions of sulfur were he'ated for approximately two to three and comprising the reaction between the corresponding amine and sulfur in the presence of a catalyst or condensing agent, for example iodine.

From an analysis of the resulting product, it is believed the reaction between sulfur and pethoxy-phenyl-beta-naphthylamine takes .place in the following manner:

' All of the materials hereinbefore cited on incorporating in a standard rubber stock and vulcanizing and then artificially aging in the manner hereinbefore set forth were found to possess desirable antioxidant properties. In no case did the vulcanized rubber sto'ck melt down in the bomb during the aging process.

In all the examples hereinbefore given diphenyl-guanidine was employed as an accelerator because it is known to produce a vulcanized rubber stock that has poor aging qualities. Other accelerators than diphenyl-guanidine could of course be employed in conjunction with the preferred class of anti-oxidants and in the manner as described. v

The invention is to be understood as limited solely by the claims attached hereto as a part of this specification wherein the invention is claimed as broadly as possible in view of the prior art.

The present application is an improvement over my application, Serial No. 362,128 filed May 10, 1929.

What is claimed is:

1. The method of preserving rubber which comprises treating rubber with a sulfur derivative of a diaryl amine, a phenyl radical of said diaryl amine containing a nuclear alkoxy substituent only.

2. The method of preserving rubber which comprises treating rubber with a sulfur derivative of a diaryl amine, a phenyl radical of said diaryl amine containing a nuclear ethoxy substituent only.

3. The method of preserving rubber which comprises treating rubber with a sulfur derivative of p-ethoxy phenylbeta naphthyl amine.

4. A rubber composition comprising rubber and a sulfur derivative of a diaryl amine, a phenyl radical of said diaryl amine containing a nuclear alkoxy substituent only.

5. A rubber composition comprising rubber and a sulfur derivative of a diaryl amine, a phenyl radical of said diaryl amine containing a nuclear ethoxy substituent only.

6. A rubber composition comprising rubber and a sulfur derivative of p-ethoxy phenyl beta naphthyl amine.

'7. The method of preserving rubber which comprises treating rubber with a sulfur derivative of a phenyl beta naphthyl amine, one of the nuclear hydrogen atoms of said phenyl group being substituted by an unsubstituted alkoxy group only.

8. .A rubber composition comprising rubber and a sulfur derivative of a phenyl beta naphthyl amine, one of the nuclear hydrogen atoms of said phenyl group being substituted by an unsubstituted alkoxy group only.

comprises treating 9. The method of preserving rubber which comprises treating rubber with a sulfur derivative of an amine of the structural formula wherein R. represents a phenyl radical and R represents an unsubstituted naphthyl radical, said phenyl radical containing an ethoxy substituent only.

10. A rubber composition of matter comprising rubber and a sulfur derivative of an amine of the structural formula wherein R represents a phenyl radical and R represents an unsubstituted naphthyl radical, said phenyl radical containing an ethoxy substituent only. v

11. The method of preserving rubber which rubber with a sulfur derivative of a phenyl beta naphthyl amine, said phenyl radical being substituted by an ethoxy group only.

12. A rubber composition comprising rubber and a sulfur derivative of a phenyl beta naphthyl amine, said phenyl radical being substituted by an ethoxy group only.

WINFIELD SCOTT. 

